| 摘要 |
Disclosed are a high-strength hot-rolled steel sheet having transformation-induced plasticity grain in a hot-rolled state, and a manufacturing method thereof. According to the present invention, the method to manufacture a hot-rolled steel sheet comprises the steps of: hot-rolling, at a temperature higher than or equal to Ar3, a slab plate composed of 0.14-0.17 wt% of carbon (C), 1.40-1.60 wt% of silicon (Si), 1.40-1.60 wt% of manganese (Mn), 0.02 wt% or less of phosphorus (P), 0.003 wt% or less of sulfur (S), 0.045-0.055 wt% of titanium (Ti), 0.45-0.55 wt% of chromium (Cr), and the remainder consisting of iron (Fe) and inevitable impurities; primarily cooling the hot-rolled plate to a ferrite region; keeping the primarily cooled plate cooled by air in the ferrite region for 5 seconds or longer; secondarily cooling the air-cooled plate to a bainite region; and winding the secondarily cooled plate in the bainite region. |
